I have had 2 different occassions in roughly the same area that were hostile feeling with intensity with the animal showing itself only while I retreated from the area in a slow fashion.
I don't think the same animal was involved in both cases. Both times they shadowed me out and both times the animals came out into full view. I never heard vocals or any other intimidating sounds like breaking limbs. Both times I just had all the hair stand up on my body and all my senses told me to leave something was wrong ( nothing indicated another animal, BTW).
It wasn't until I got to either most of the way to my 4wheeler or actually on my 4 wheeler did they make themselves visable. but both of them used their size to show themselves off. one walked off to the road my 4wheeler was on and smacked a good sized tree to shake back and forth. the other one raised one arm to grab I higher limb. I think to make himself look bigger.